1. Field of the Invention
The present invention relates to a developing method and developing apparatus each for developing an exposed pattern after a resist film formed on a substrate such as a semiconductor wafer, an LCD substrate, or the like is exposed in a predetermined pattern.
2. Description of the Related Art
In a coating and developing system for a photolithography process in processes of semiconductor device fabrication, for example, resist coating processing for forming a resist film on the front surface of a semiconductor wafer and developing processing for developing the wafer after performance of exposure processing for the resist-coated semiconductor wafer are performed.
In the developing processing, the wafer which has undergone exposure in a predetermined pattern, post-exposure bake processing and cooling processing is carried into a developing unit to be mounted on a spin chuck. A developing solution is supplied from a developing solution supply nozzle and applied (heaped up) so as to have a thickness of 1 mm, for example, on the entire surface of the semiconductor wafer, and thus a developing solution puddle is formed. The wafer stands still for a predetermined period of time with the developing solution puddle being formed, and developing processing progresses by natural convection. Thereafter, the developing solution is blown off by the semiconductor wafer being rotated by the spin chuck, and then a rinse solution is discharged from a rinse solution supply nozzle to wash away the developing solution remaining on the wafer. Subsequently, the spin chuck is rotated at a high speed, whereby the developing solution and the rinse solution remaining on the semiconductor wafer are blown away so that the wafer is dried. Thus, a series of developing processing is completed.
When the developing solution puddle is formed in this developing processing, nozzles of various shapes are used for applying the developing solution onto the entire surface of the semiconductor wafer, and the wafer is rotated and the nozzle is scan-moved while the developing solution is being discharged from the nozzle.
In the aforesaid prior developing method, however, the time to heap up the developing solution, impact at the time of supply of the developing solution, displacement speed of the developing solution, and the like are uneven in the surface of the semiconductor wafer by any means when the developing solution puddle is formed on the semiconductor wafer, thereby making it difficult to obtain uniformity of line width. Moreover, defects are prone to occur due to entrance of bubbles in heaping up the liquid and the like.
Recently, with high integration of devices from 64 megabytes to 256 megabytes, it is increasingly demanded to make circuit patterns more minute, and the minimum line width almost reaches a super-submicron region of not more than 0.2 .mu.m. In order to meet the demand, a chemically amplified resist is used as a resist capable of micromachining, but the chemically amplified resist has poor wettability for the developing solution, so that the aforesaid defects are prone to occur. When micromachining is performed with the chemically amplified resist, the ununiformity of line width due to the aforesaid unevenness becomes remarkable because of quite high sensitivity of the chemically amplified resist for the developing solution.